I guess I'll have to remember how to search the A1200 for the cross-dos devices. Even the words 'CLI' and 'Device List' are ancient foggy memories I'm struggling to resurrect... I guess that's part o' the fun?
Indeed.
CLI: Command Line Interface, what you get when you double-click the Shell icon in the System drawer of your main disk (Workbench or whatever it is called on your machine).
Once you are in the CLI, at the prompt, you can e.g. type "info" and hit Enter. This will show, among other things, the devices you have mounted. If PC0 is one of them, you are okay, then you should get a PC0 icon on your Workbench if you insert a PC-formatted DD (i.e. 720 kB) diskette.
Apart from that, follow AndyFC's advice above about checking inside Devs/DOSDrivers (i.e. open the Devs drawer in your Workbench disk, then open the DOSDrivers drawer inside that.) - if you don't have a PC0 icon in there, you may have it in Storage/DOSDrivers, then just drag it from there into Devs/DOSDrivers, and afterwards do a reset.
Best regards,
Niels